a) Field of the Invention
The invention relates to a medical handpiece for transmitting energy from a laser beam into biological tissue in which an optical fiber for conveying the laser radiation and a light guide for radiating the laser energy into the tissue are arranged in a base body.
b) Description of the Related Art
Known handpieces of the type mentioned above have a fixed connection between the light guide and the base body of the handpiece. In this regard, it has been shown that the light guides, which are generally made of quartz or sapphire, wear out after about four operations. The reason for this is that the polished fiber end which comes into contact with the tissue becomes coarsened and is no longer effective for removal. This happens especially with high laser pulse trains and probably results from the formation of cavitation bubbles.
It is disadvantageous that the light guides cannot be exchanged. Accordingly, the entire applicator must be exchanged when the light guide is worn. Because of the permanent connection, not only is the light guide forfeited at the end of the possible period of use, but also the base body and other essential functioning parts of the handpiece are wasted.
A further disadvantage is that the handpiece is difficult to clean because of the very narrow intermediate spaces between the structural component parts in the assembled state. Thus, the space between the cannulae (diameter less than 1 mm) and the light guide (diameter greater than 0.4 mm) must be cleaned completely hygienically; for this purpose, it would be desirable to have a handpiece which could be disassembled, but this would require excellent adjustability of essential functional parts.
U.S. Pat. No. 4,785, 805 describes a device for coupling a laser beam coming from its source into a light guide, wherein a collecting lens is arranged in front of the light guide. This device refers to technical means for achieving a centering of the optical axes of the collecting lens and light guide relative to one another as a precondition for coupling in with the least possible losses. However, in this case there is no need, nor are any technical means provided for this purpose, to align the optical axes of the collecting lens and light guide relative to a suction cannula within which the light guide is to extend in a definite position as is the case in a handpiece of the type mentioned above.
To this extent, this device does not satisfy the requirements for use in such a medical handpiece because this medical handpiece requires that the light guide can be removed when worn and that it can be exactly replaced by a new light guide and aligned in a simple manner with the optical axis of the fiber and suction cannula. Also, a handpiece frequently requires disassembly for purposes of cleaning and, for reasons of time and cost, also requires a subsequent simple realignment of the optical axes and suction cannula. This requirement is not met in the device in the above-cited publication.
An adapter for light guide input coupling for a laser device is described in EP 0 507 991. The adapter contains a sleeve-shaped fitting part for receiving the proximal end of the light guide and is constructed in such a way that blocking and coupling mean are provided in the region of the connection point between the fitting part and a handle, these means enabling the connection of the fitting part and handle only when the light guide is inserted. A light guide for radiating laser energy into biological tissue, for example, which light guide is subject to wear and must therefore be changed frequently and aligned with another light guide and also with a suction cannula in which it extends whenever it is changed, is not provided herein. Consequently, the means disclosed in this reference are not suited to an adequate solution of the above-indicated problems relating to a handpiece.
This relates in an analogous manner to the rinsing catheter according to DE 41 26 886 A1. This rinsing catheter is used to eliminate solids from bodily organs and vessels in humans and animals and is provided with at least two lumens, one of which serves to supply a rinsing fluid from a high-pressure fluid source to the organ in question, while the second lumen is provided for carrying the rinsing fluid and the solids particles entrained by the rinsing fluid out of the organ.
However, there is no transmission of energy by laser via light guides or a coupling in of this energy provided in this reference, and the means indicated in this disclosure also do not solve the problem of an essentially automatic alignment of two light guides with respect to their optical axes and also with respect to a suction cannula for assembly after cleaning or after exchanging one of the light guides.
U.S. Pat. No. 4,785, 805 describes a device for coupling a laser beam coming from its source into a light guide, wherein a collecting lens is arranged in front of the light guide. This device refers to technical means for achieving a centering of the optical axes of the collecting lens and light guide relative to one another as a precondition for coupling in with the least possible losses. However, in this case there is no need, nor are any technical means provided for this purpose, to align the optical axes of the collecting lens and light guide relative to a suction cannula within which the light guide is to extend in a definite position as is the case in a handpiece of the type mentioned above.
To this extent, this device does not satisfy the requirements for use in such a medical handpiece because this medical handpiece requires that the light guide can be removed when worn and that it can be exactly replaced by a new light guide and aligned in a simple manner with the optical axis of the fiber and suction cannula. Also, a handpiece frequently requires disassembly for purposes of cleaning and, for reasons of time and cost, also requires a subsequent simple realignment of the optical axes and suction cannula. This requirement is not met in the device in the above-cited publication.
An adapter for light guide input coupling for a laser device is described in EP 0507991. The adapter contains a sleeve-shaped fitting part for receiving the proximal end of the light guide and is constructed in such a way that blocking and coupling mean are provided in the region of the connection point between the fitting part and a handle, these means enabling the connection of the fitting part and handle only when the light guide is inserted. A light guide for radiating laser energy into biological tissue, for example, which light guide is subject to wear and must therefore be changed frequently and aligned with another light guide and also with a suction cannula in which it extends whenever it is changed, is not provided herein. Consequently, the means disclosed in this reference are not suited to an adequate solution of the above-indicated problems relating to a handpiece.
This relates in an analogous manner to the rinsing catheter according to DE 41 26 886 A1. This rinsing catheter is used to eliminate solids from bodily organs and vessels in humans and animals and is provided with at least two lumens, one of which serves to supply a rinsing fluid from a high-pressure fluid source to the organ in question, while the second lumen is provided for carrying the rinsing fluid and the solids particles entrained by the rinsing fluid out of the organ.
However, there is no transmission of energy by laser via light guides or a coupling in of this energy provided in this reference, and the means indicated in this disclosure also do not solve the problem of an essentially automatic alignment of two light guides with respect to their optical axes and also with respect to a suction cannula for assembly after cleaning or after exchanging one of the light guides.
It is the object of the invention to enable an uncomplicated exchange of the light guide and, further, with little effort on disassembly and assembly to ensure perfect cleaning which satisfies all hygienic requirements.
In a medical handpiece of the type described above, this object is met in that, for purposes of alignment of the optical axis of the light guide with respect to the longitudinal axis of the suction cannula as well as with respect to the optical axis of the radiation-side end of the fiber, at least one adjusting face is allocated in each instance to the light guide, the suction cannula and the fiber so as to be fixed in place, wherein at least one of the adjusting faces assigned to the light guide corresponds with an adjusting face assigned to the suction cannula and with an adjusting face assigned to the fiber, and wherein the light guide is displaceable in the axial direction relative to the base body and the alignment can be produced or canceled depending on the displacement direction.
This construction offers the substantial advantage that the light guide used for radiating laser energy into the tissue is separate from the optical fiber by which the laser radiation is guided from the laser source to the handpiece and can be removed from the handpiece with little effort and exchanged for an unused light guide. The removal of the light guide from the base body of the handpiece is made possible by displacing in the axial direction opposite to the radiation direction of the laser radiation. Conversely, the insertion of the new light guide can be carried out by inserting and pushing forward in the axial direction into the base body of the handpiece, wherein an automatic alignment of the light guide is carried out inside the suction cannula through which the biological tissue which is comminuted by the effect of the laser energy is sucked off from the treatment site. The alignment of the optical fiber is effected relative to the base body of the handpiece and accordingly also relative to the light guide at the same time, while the optical end of the fiber is pushed into the handpiece and centered.
To this extent, means for alignment of the optical axis of the light guide with respect to the longitudinal axis of the suction cannula as well as with respect to the optical axis of the radiation-side end of the fiber are provided in a medical handpiece which has a suction cannula for the comminuted biological tissue in which the light guide extends also. The light guide is also displaceable in the axial direction relative to the suction cannula and the alignment is produced or canceled with the displacement.
It is accordingly ensured with little manual effort that after assembly or after exchanging a used light guide, the light guide will occupy the position provided within the handpiece, and accordingly also within the suction cannula, necessary for the success of the medical treatment. With respect to the cross section of the suction cannula, which is preferably round, the light guide which is also constructed with a round cross section can be arranged centrically. However, an advantageous alternative consists in arranging the light guide so as to be offset with respect to the center of the suction cannula, so that there remains a larger cross-sectional area through which the particles resulting during treatment can be sucked off.
For purposes of alignment, adjusting faces are allocated to the base body and to the light guide, wherein alignment is achieved when these adjusting faces contact directly. Alternatively, these adjusting faces can be constructed as circular-cylindrical faces which form a sliding fit and which are accordingly displaceable relative to one another in the axial direction, or the adjusting faces can be formed as circular-conical faces with an automatically centering slope. One of the surfaces, either the cylindrical surface or the circular-conical surface, is formed as an inner surface while the opposite surface is formed as the outer surface. Further, each centering surface has a circular cross section. The freedom of movement in the axial direction is limited by stops. In this respect, it can be provided that a mechanical spring or a body of elastic material is arranged between the stops, wherein a pretensioning force is generated by the displacement in the axial direction and the pretensioning force can be increased or reduced by the extent of displacement in the axial direction. Further, sealing elements can be provided between the adjoining portions of the stop faces.
The invention is explained more fully in the following with reference to an embodiment example.